On Tue, Aug 12, 2014 at 06:08:21PM +0530, shashank.sharma@xxxxxxxxx wrote: > From: Shashank Sharma <shashank.sharma@xxxxxxxxx> > > During the HDMI complaince tests, most of the HDMI analyzers > issue a soft HPD, to automate the tests. This process keeps > the HDMI cable connected, and DDC chhanel alive. > > HDMI detect() logic relies on EDID readability, to decide if > its a HDMI connect or disconnect event. But in this case, the > EDID is always readable, as HDMI cable is physically connected > and DDC channel is UP, so detect() always reports a HDMI connect > even if its intended to be a HDMI disconnect call. > > So if HDMI compliance is enabled, we should rely on the live status > register, than EDID availability. This patch adds: > 1. One kernel command line parameter for i915 module, which indicates > if we want to support HDMI compliance, for this platform. I would rather have this as an output property. In fact, I would like the hotplug detection method exposed (and even selectable, but other than this compliance testing, I can't think of a scenario where the kernel shouldn't be able to figure things out for itself). > 2. A new function to read EDID, which gets called only in case of > HDMI compliance support is required. This function reads EDID only > if live status register is up. The normal code flow doesn't get effected > if kernel command line parameter is not enabled. > 3. After various experiments on VLV2 board, with various HDMI monitors > we have seen that, with few monitors, the live status register gets > set after a slight delay, and then stays reliably. To support such > monitors, there is a busy-loop added, with a max delay upto 50ms, > with a status check after every 10ms. Please see the comment in > intel_hdmi_get_edid. Wouldn't a tidier solution be to delay the hpd by 50-100ms after the hotplug interrupt? That may overcome the issue with the live status for all connectors... -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
